The present invention relates to an electrographic recording device for use in an information processing apparatus such as computer or facsimile and, more particularly, to a multi-pin electrode assembly employed in the electrographic recording device, and also to a method for manufacturing the same.
The multi-pin electrode assembly known in the art, as shown in FIG. 1, includes a plurality of pin electrodes which are generally indicated by a reference character PN and are parallely aligned to each other with tip ends PN.sub.1 thereof being in alignment with each other. The plurality of pin electrodes may be provided over a suitable substratum A, and the tip ends PN.sub.1 thereof may be rigidly supported on the substratum A and held between a pair of supporting bar members B.sub.1 and B.sub.2. While the pin electrodes PN are thus aligned, the pin electrodes are divided, after every m pin electrodes from the pin electrode positioned at one end of the alignment, into n groups, which are indicated by reference characters G.sub.1, G.sub.2, . . ., G.sub.i, . . ., G.sub.n, respectively, and each group, represented by a group G.sub.i, as schematically shown in FIG. 2, includes m pin electrodes which are indicated by reference characters i-1, i-2, . . ., i-i, . . ., i-m, respectively. It is to be noted that n and m are any numbers and i is a number smaller than n or m. All the first electrodes 1-1, 2-1, . . ., i-1, . . ., n-1 in each group are connected to each other to terminate at a first terminal T.sub.1, and in similar manner, the rest of the corresponding electrodes which are positioned at the same place in each group are connected to each other to terminate at respective terminals T.sub.2, T.sub.3, . . ., T.sub.i, . . ., T.sub.n.
The multi-pin electrode assembly, as described above, is generally employed in the electrographic recording device as a recording head where it is so arranged as to constitute an electrostatic recording system. Among various types of recording systems, the electrostatic recording system is known for its high-speed procedure in the process of recording the information.
The electrographic recording device includes, as shown in FIG. 2, the multi-pin electrode assembly having the terminals T.sub.1, T.sub.2, . . ., T.sub.n connected to respective signal source (not shown), and a set of electrode array of opposite electrode with respect to the pin electrode. The electrode array includes electrode plate members P.sub.1, P.sub.2, . . ., P.sub.i, . . ., P.sub.n which are separated from each other and are aligned to each other along the alignment of the pin electrode tip ends PN.sub.1 in a spaced relation thereto by the amount of S.sub.1. As apparent from FIG. 2, the plate members P.sub.1, P.sub.2, . . ., P.sub.n are positioned in face to face relation with the pin electrode tip ends included in the groups G.sub.1, G.sub.2, . . ., G.sub.n, respectively. The electrostatic recording is effected by a discharge of charged film F of dielectric material provided over a recording medium M which moves past the space S.sub.1. While the recording medium M moves past the space S.sub.1, i.e., between the opposite electrodes, the voltage applied therebetween produces an arc discharge at an extremely narrow space S.sub.2 formed between the pin electrodes and the film F, so as to form a latent image on the film F. The film having passed through the space S.sub.1 is, then, coated with spread toner particles which are charged in opposite polarity to that of the film to turn or develop the latent image into a visual image. Thereafter, the film is suitably processed to fix the visual image on the film.
According to such electrographic recording device, the pin electrode assembly of conventional type is prepared through the following steps.
First, the substratum A made of comparatively flexible material is formed into a cylindrical form, as shown in FIG. 3, preferably wrapped around a core C. Then, an insulated thin wire, which will serve as pin electrodes, is spirally wound around the cylinder A in high density such as 8 turns/mm. The number of turns for preparing the above described pin electrode assembly is equal to m times n turns. In order to hold the wound wire thereon, the outer surface of the cylinder may be coated with an adhesive material, or otherwise, a strip of adhesive tape may be extended over the wound wire. Then, the pair of supporting bar members B.sub.1 and B.sub.2 are positioned correspondingly outside and inside of the cylinder for tightly holding the cylinder therebetween together with the wire. Thereafter, the cylinder, together with the wire, is cut along a line L-L' which is extended closely adjacent the longitudinal edge of the bar members B.sub.1 and B.sub.2 so as to be spread out into the substratum A to form the pin electrode assembly shown in FIG. 1. The pin electrode on the substratum A are divided into a plurality of groups as in the manner described above, and the pin electrodes positioned at the same place are connected to each other and further to respective terminals.
In the conventional pin electrode assembly as described above, the operations of dividing the pin electrodes into plurality of groups and connecting the corresponding pin electrodes are carried out by skilled workers, since such operations are comparatively difficult to be taken over by an automatically operating machine. Therefore, there have been such drawbacks in the conventional pin electrode assembly that the groups may not include a required number of pin electrodes or that the pin electrodes might be erroneously connected to the terminals due to misleading or miscounting of the electrodes especially when the number of the pin electrodes in one group increases or when the density of the electrode becomes higher than 8 pin electrode/mm. Furthermore, it has taken a comparatively long period of time before completing one pin electrode assembly.